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<br />Irrigation Methods in Virgin Valley - Methods are random flooding, <br />graded and level borders, corrugations, furrows and sprinkler. The <br />predominate method used is graded borders. <br /> <br />The present onfarm irrigation efficiency, based on an analysis <br />of 17 percent of the irrigated acreage in Virgin Valley, averages 44 <br />. <br />percent. Deep percolation in Virgin Valley is estimated to be 19,000 <br />acre-feet annually. <br /> <br />Conservation practices presently applied on irrigated and adjacent <br />lands include: <br /> <br />Brush Management <br />Clearing and Snagging <br />Conservation Cropping Systems <br />Crop Residue Management <br />Irrigation Ditch and Canal <br />Lining <br />Irrigation Field Ditch <br /> <br />Irrigation Water Management <br />Irrigation Land Leveling <br />Land Smoothing <br />Structures for Water Control <br />Wildlife Wetland Habitat Management <br />Wildlife Upland Habitat Management <br /> <br />Land Resource <br /> <br />Soil Survey and Land Classification - Variations in climate, biolo~ <br />ica1 forces, relief, parent materials and age of land surfaces within <br />the study area have resulted in a complex pattern of soils and miscel- <br />laneous land area. Soil orders represented include Aridisols and Entiso1s <br />known to be potential sources of salts and sediments in the water resources. <br /> <br />"'" <br /> <br />The following descriptions indicate the general character of the <br />soil associations in the study area. See the Soils Map, Figure 11. <br /> <br />Toquop Association: Deep, excessively drained, nearly level to <br />moderately sloping soils; on alluvial fans. Surface soil is fine sand. <br /> <br />r,,~ <br /> <br />Toquop-Virgin River Association: Deep, excessively drained, some- <br />what poorly drained, nearly level to moderately sloping soils; on flood <br />plains, and alluvial fans. Surface soil is fine sand, or silty clay. <br /> <br />Mormon Mesa-F1attop-Arada Association: Shallow to deep, well <br />drained and somewhat excessively drained, nearly level to moderately <br />sloping soils; on Mormon Mesa and on terraces and alluvial fans. In the <br />study area the surface soil is fine sandy loam or fine sand. <br /> <br />;?: <br /> <br />Bad1and-Bard-Tonopah Association: Badland, and moderately deep and <br />deep, well drained and excessively drained, nearly level to strong slop- <br />ing soils; on old terraces and alluvial fans. Badland consists of <br />severely eroded and gullied areas. It is highly stratified deposits <br />of silt and clay that contains a large amount of gypsum and calcium <br />carbonate. The other units are gravelly sandy and fine sandy loam. <br /> <br />20 <br /> <br />", J- '. r. ,.......... <br />v: l... j , <br />